This invention relates to pneumatic plugs and flow-through diverters that are frequently used in piping systems during inspection and repairs. Various pneumatic devices having expandable bladders have been used in piping systems to block the flow, in a pipe or a conduit, preventing fluids, primarily liquids, from flowing through the pipe or conduit, particularly at the location of a work area. The use of pneumatic devices as blocking plugs, diverters or repair devices is well known in the industry. For example, this inventor has designed and patented a xe2x80x9cPipe Joint Testing and Grouting Unitxe2x80x9d disclosed in U.S. Pat. No. 5,066,208, issued Nov. 19, 1991. The device of the referenced patent includes a rigid cylindrical core having an outer pneumatic bladder that can be inflated by the use of a pressurized fluid such as air. When the unit is placed at a joint that is in need of repair, a repair cement can be pumped through a connecting line to the perimeter of the inflated bladder to fill any void in the joint.
Other inflatable devices have been fabricated which allow the flow of a pipe or conduit to be diverted through a diversionary conduit by the use of an inflatable plug-like unit having a core with an attachable conduit such as a flexible hose to divert the liquid flow through the pipe under repair to a downstream location or to another holding area. This diverter unit is usually constructed with an inflatable plug having a rigid cylindrical core having an end with a permanent or replaceable end plate. The end plate has a projecting nipple for connecting a flexible hose or pipe using a clamp to clamp the flexible hose to the nipple.
There are situations when using a flow diverter unit where control of the rate of flow is desired. For example, in diverting the flow through a manhole during rehabilitation of the manhole, it is advantageous to stop and start the flow during hook-up.
In the preferred embodiment, the central rigid core provides a stable mounting surface for the projecting pipe segments that, in the usual case, connect to the air hoses of a compressor. Independent regulation of the air pressure in the respective inner and outer bladders is accomplished at the air compressor in a conventional manner. The variable flow-through control plug is designed with a rigid core sized to maximize the flow through the unit. In this manner, the units are preferably offered in a series of sizes to accommodate different sizes of conduit, for example, sewer pipe that require a controllable blockage.
The flow-through control plug of this invention is designed for installation within a pipe or conduit where the flow must be regulated or blocked according to conditions arising at the site. Other uses will become apparent to those in the field. As noted, customarily, the variable flow-through control plug is used in conjunction with a flow diverter allowing a section of a water flow system to be bypassed for repair or inspection.
The variable flow control plug of this invention is designed with a central rigid core that is substantially cylindrical in configuration. Around the core is an annular bladder that is expanded typically using pressurized air. In addition, an internal bladder that is annular in configuration is secured to the rigid core and similarly inflated by pressurized air.
For example, in a standard manhole unit of a sewer system, water flows into the manhole through an entry conduit and out the manhole through an exit conduit, the manhole functioning as a surge basin and pressure relief. During rehabilitation of the manhole, it is desirable to connect the entry conduit with the exit conduit. Use of the invented flow-through control plug connected to a conventional flow through diverter by a flexible duct allows water flow from the entry conduit to the exit conduit to be stopped or regulated. Furthermore, installation of the flow-through control plug during high flow conditions can be facilitated by allowing flow during positioning and inflation of the outer bladder, and blocking flow after the unit is properly seated. Connection of a flexible diverter duct, with or without a complimentary flow through diverter, can then be accomplished with a blocked water flow.
It is to be understood, that in certain situations it may be desirable to expand the bladders using a gas other than air or using a liquid such as water. For example, where the flow-through control plug is used in a conduit system for transporting fuel or an explosive gas, it is desirable that a gas such as nitrogen or carbon dioxide be used.
These and other features will become apparent from considering the detailed description of the preferred embodiment that follows.